In dimly lit, dark, or completely dark situations it may be desirable for a light source be available for the safety and/or convenience of those finding themselves in such conditions. Battery-powered or electric light sources such as lanterns, headlamps and flashlights are not always available or effective because of power loss or limited sight distance. Ordinary lighting devices are typically not capable of leaving an illuminated trail that could be followed by one coming after or exiting the way the person leaving the trail has traveled, without leaving such device behind. Phosphorescent flares or other phosphorescent based light sources may be left behind to guide one coming after or exiting the way the person leaving the trail has traveled. However, phosphorescent light sources may be dangerous in situations where the smoke and the sparks they produce could be harmful.
A situation may be such that there are gasses, fumes or other flammable materials known or unknown in close proximity which could be ignited by the phosphorescent flares or other phosphorescent based light sources. For example, using a phosphorescent light source during a spelunking or caving outing could lead to an explosion from gaseous vapors that have built up underground. Both of these light sources are also problematic when a person in a dimly lit or completely dark situation wants to light what is in front of him or her a significant distance away, such as down a hole or further down a tunnel.
An optional light source available to people who find themselves in dark situations are chemiluminescent-based light sources. Those are usually found in the form of light sticks or glow sticks. These work by having chemicals in separate compartments. When the compartments are ruptured, the materials mix and interact to cause illumination, However, if the goal is to leave a trail to exit or for a person following behind, and the trip is an especially long one, it becomes impractical to carry the number of light sticks which may be necessary to create such a trail. Another disadvantage is that these light sources must be left on some type of generally horizontal surface and are not easily deposited on a vertical surface unless other materials, such as adhesives, fasteners, etc, are available.